RESUMO
The increase of revision surgeries in hip replacement procedure in Colombian young adult population can be addressed by a new design of femoral stem that reduces stress shielding. A new femoral stem was designed using topology optimization as a design aid to reduce the mass in the femoral stem and its overall stiffness, combined with the theoretical, computational, and experimental assessment of the new design that complies with a static and fatigue safety factor greater than one. The new femoral stem design can be used as a design tool to reduce the number of revision surgeries caused by stress shielding.
RESUMO
The endurance properties of a femoral stem under fatigue loading must be known and the methodology proposed in this work provides the mathematical tools for designers of femoral stems and orthopedic surgeons to select the adequate material and femoral stem design with a new graph that condensate the information in an easy to use selection process. Initially, the theoretical and computational development of the fatigue analysis provides comparable results with an average error of 8.3%. And the formulated methodology with the aim of selecting the mechanical device with the best fatigue performance with an average error of 8.7%.
Assuntos
Prótese de Quadril , Estresse Mecânico , Desenho de Prótese , Fêmur/cirurgia , Análise de Elementos FinitosRESUMO
The maximum stresses on a femoral stem must be known for selecting the right size and shape of the shaft cross-sectional area for reducing the stress shielding effect generated after the total hip arthroplasty (THA) surgical procedure. The methodology proposed in this study provides the tools to the designers of femoral stems and orthopedic surgeons to select the adequate femoral stem cross section, decreasing the stiffness of the stem, thus reducing the stress shielding effect in the patient bones. The first contribution is the theoretical development of the maximum static stress calculation for 12 different femoral stem models with the beam theory, followed by the comparison with the static finite element analysis (FEA) simulations and finally the experimental corroboration of one femoral stem model measuring the strain with linear strain gages and transform it to stresses, the three different approaches provide comparable results, with a maximum average error of less than 8.5%. The second contribution is the formulation of a new selection methodology based on maximum stresses in the femoral stem and the cross section area for decreasing the stress shielding effect, optimizing the area needed for withstand the loads and decreasing the overall stiffens of the stem.